Cut Out
An open area in a raised floor that allows airflow or cable feeds.
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Leave a Comment (0) →Current Transformer (CT)
A device used to transform electrical current from one level to another with a specific ratio. For example, a 5000:5 current transformer transforms current on the primary side to current on the secondary side with a ratio of 1000:1. CTs are typically used to transform large currents to much smaller currents so that standard metering equipment can be used on a variety of circuits by measuring the secondary current rather than the large primary current.
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Leave a Comment (0) →Cubic Feet per Minute (CFM)
A unit of flow rate, commonly used to specify airflow.
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Leave a Comment (0) →Critical Load
Computer equipment whose uptime is critical, typically supported by a UPS.
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Leave a Comment (0) →Cooling Tower
A device which cools water via the direct evaporation of some of the water. Water is pumped into the top of the cooling tower and allowed to run down over the fill, typically pads or strips into a sump at the bottom of the cooling tower. Air is drawn in from the sides over the fill by fans in the top of the tower, evaporating some of the water which cools the remaining water. The temperature of the water in the sump is controlled by varying the speed of the fans. The water in the sump is then used to cool the condensing section of a chiller or to cool the secondary loop directly via a heat exchanger (see water side economizer).
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Leave a Comment (0) →Containment
Using some type of physical barrier between a hot or cold aisle, for example, long plastic curtains or rigid plastic. Keeping warm exhaust air away from the intake of the server racks is a crucial part of making any data center more efficient.
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Leave a Comment (0) →Container
Data center container is a self contained module often produced inside a custom built shipping container, that includes a series of rack-mounted servers along, its own lighting, air conditioning/de-humidification and Uninterruptable Power Supply (UPS).
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Leave a Comment (0) →Computer Room Air Handler (CRAH)
Pronounced craw or cray, which uses chilled water passing through a heat exchanger to cool air flowing over the heat exchanger.
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Leave a Comment (0) →Computer Room Air Conditioner (CRAC)
Pronounced crack, which uses refrigerant and a compressor. Cooling of the air in the data center is accomplished by airflow over the evaporation coils where the refrigerant is being “directly expanded”+A19.
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Leave a Comment (0) →Computational Fluid Dynamics (CFD)
A numerical analysis technique commonly used in the analysis of airflow in data centers.
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Leave a Comment (0) →Cold Supply Infiltration Index (CSI)
Quantifies the amount of hot air mixing with cold inlet air prior to entering the rack.
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Leave a Comment (0) →Cold Spot
An area where ambient air temperature is below desired levels. Typically caused by ineffective airflow management necessitating a temperature set point lower than that which would be required with proper airflow management.
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Leave a Comment (0) →Cold Aisle Containment (CAC)
Cold Aisle Containment system that directs cooled air from air conditioning equipment to the inlet side of racks in a highly efficient manner.
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Leave a Comment (0) →Cold Aisle
An aisle where rack fronts face into the aisle. Chilled airflow is directed into this aisle so that it can then enter the fronts of the racks in a highly efficient manner.
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Leave a Comment (0) →Coefficent of Performance (CoP)
Used to rate the effectiveness of heat pumps or cooling units. It is the ratio of the load on a cooling unit and the energy that it uses.
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Leave a Comment (0) →Coefficent of Effectiveness (CoE)
Uptime Institute metric based on the Nash-Sutcliffe model efficiency coefficient.
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Leave a Comment (0) →CMDB
Configuration Management DB. It is the database that contains all relevant about the systems, applications, and configuration.
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Leave a Comment (0) →Close-Coupled Cooling
Cooling technology that is installed adjacent to server racks, minimizing the path that air must flow from the cooling unit through the IT equipment and back to the cooling unit.
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Leave a Comment (0) →Chiller
A unit consisting of a compressor, a condensing section and an expansion section. The condensing and expansion sections nearly always have water or glycol as the heat transfer agent to the rest of the system; primary water/glycol on the condensing side and secondary water on the expansion side.
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Leave a Comment (0) →Carbon Usage Effectiveness (CUE)
A metric defined by the Green Grid, which is a measure of data center sustainability in terms of data center specific carbon emissions. CUE is calculated by dividing the total CO2 emissions caused by total data center energy by the energy consumption of the IT computing equipment. An alternative way to calculate CUE is by multiplying the data center’s annual PUE by the Carbon Emissions Factor for the region as determined by the EPA. The units of CUE are kilograms of carbon dioxide per kilowatt-hour.
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